posted 06-21- 08:28 AM               

When I open a TIF for a plane, what I find is a whole bunch of "subtiffs" inside. How does a particular one of these get mapped onto the right part on the plane? When I look in OPS, I don't see anything obvious to suggest how this works.

Another question, what if I have a LOD with a proper switchin, but no texture? Does the object in question simply not appear?

posted 06-21- 09:40 PM               

Each vertex of the mesh gets an additional 2 dimensional coordinate assigned to it - called the UV coordinate. The values are from 0 to 1 (for non-repeating textures).

0,0 is one corner of the texture graphic, and 1,1 is the opposite corner. It is the job of the 3d modeling editor to help you assign the coordinates to the vertecies.. this is called "texture mapping."

Little 3d apps like AC3D tend to use only projection mapping... you line up your 3d object in an ortho view window.. then use a widget or a square polygon that has the full texture graphic on it... you size and position the square sheet so that it falls over the object you want to texture. You then map the texture... this will set the UV coords of the object based on where the widget is.

So now if you scale the object in the 3d app, the texture map is not harmed... because it is unrelated to the graphic size or object size... just proportions (0 to 1).

If you move verts, it will stretch the texture in odd ways.

Fancy modeling tools like 3dsmax let you map sphericaly, and like a cylinder, etc.

You do need to map the lower detail LODS if you want to use a texture on them.

Another trick: generally, you map an entire wing all at once. Then you break out the ailerons, etc. This way all the textures align perfectly.

Texture mapping is 80%+ of 3d modeling work. It also has the most room for artistic and technical expression... there are many valid approaches. A good map means a better model - and one that other artists can make better skins for... and probably more effecient texture memory use as well.

But the biggest trick of all... is smooth shading (and when not to smooth shade)